Magnetically operated tool



April 1949- Y A. J. FRANCIS, JR 2,467,376

MAGNETICALLY OPERATED TOOL Filed March so, 1944 mmmwwu mo p (fine/raw Q1 Jr-anus (in 03 m} W W, w};-

TTO nqgmys Patented Apr. 19, 1949 UNITED STATES PATENT OFFICE MAGNETICALLY OPERATED TOOL bury, Rockford, Ill.

Application March 30, 1944, Serial No. 528,696

7 Claims. 1

This invention relates to a magnetically operated tool, and more particularly to a tool in which the working instrumentality is reciprocated by a magnetically operated driving motor.

One object of this invention is to provide a magnetically operated tool having a reciprocating work-performing instrumentality or tool and magnetic and mechanical driving parts of novel and efficient construction for actuating the tool.

Another object is to energize the actuating magnet by alternating current and store energy during magnetic retraction of the working instrumentality and release during that portion of the reduced current portions of the alternating current cycles.

Another object is to provide a tool of the above character in which the motor housing not only provides an efficient magnetic structure, but firmly and efiectively holds the electromagnetic Winding in place.

The invention also resides in the novel arrangement of the parts which contributes to low cost of manufacture and effective cooling and facilitates adjustment to provide optimum magnetic efiiciency.

Further objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which Figure 1 is a vertical sectional view through a magnetically operated tool which embodies a preferred form of this invention.

Fig. 2 is a side elevational view of a portion of the structure shown in Fig. 1 with a portion cut away to show more clearly the internal structure.

Fig. 8 is a sectional view taken substantially on line 33 of Fig. 1 and viewed in the direction indicated by the arrows.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention by such disclosure but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring to the drawings, a housing It comprehends a pair of opposed cup-like elements H and I 2 which are preferably cast of magnetic or magnetizable material such as soft iron or silicon steel. The opposed cup-like members II and I2 preferably have cooperating flange portions ll and H which fit together and are secured in place by having cooperating threaded surfaces or by screws such as I5. The members H and I2 preferably have central axial bores or openings I1 and i8 and inwardly extending flanges l9 and 20 adjacent these openings and form integral portions of the housing elements H and I2 and have tapered outer surfaces radially spaced from the walls of the housing. The inner ends of the flanges l9 and 20 are axially spaced apart.

A stationary core member 22 of magnetic material extends into the housing through the bore l1 and has an end portion 23 threaded into a portion 24 of the element H. The member 22 is axially adjustable by rotation thereof with respect to the housing and is locked in adjusted position by means such as a lock nut 25. An armature 26 of magnetic material is journalecl for axial reciprocating movement in the bore [8 and extends into the housing ill in opposed relation with respect to the core member 22. The latter and the armature 26 have end portions 28 and 29 of reduced cross section to increase the flux density in the opposed pole faces.

A coil or winding 30 of the solenoid type preferably has inner end surfaces, as at 32 and 33, which are tapered outwardly and fit snugly over the flanges i9 and 20 to support the coil and hold it firmly in position. The outer surface of the :coil is preferably spaced from the inner surface of the housing ill to permit the circulation of cooling air. Leads, such as 34 and 35, are connected to the ends of the coil or winding 30, as at 36, and are adapted to connect the winding to a source of alternating current of predetermined frequency.

The sectional thickness of the housing 10, including that of the flanges l9 and 20, is preferably sufficient to provide a low reluctance flux path for the flux of the winding 30. Since this winding is mounted directly upon the flanges l9 and 20, and the air gaps between the housing and the core member 22 and between the housing and the armature 26 are minimized, the only appreciable high reluctance gap which occurs in the magnetic circuit is the working gap between the pole faces of the stationary core member 22 and the armature 26. To minimize losses due to eddy currents, a radial slot 31 extends outwardly from the center of the stationary core member 22 and along the length of that member. Likewise, a radial slot 38 is provided in the armature 26 which extends outwardly from the center of the armature and along its entire length. Eddy or stone and the like.

current losses in the flanges i9 and 20 are reduced by a plurality of slots, such as 39, which divide the flanges into sections, the housing I being preferably made from portions which are cast from solid material as distinguished from being built up of laminations. The outer surface of the housing is radially slotted as at 40 to reduce eddy current losses and provide for the circulation of cooling air.

A tubular auxiliary housing member 42, which is preferably made of non-magnetic material such as brass, is threaded into a counterbore 43 which is coaxial with the bore l8 and armature 28. An end of the armature extends into the auxiliary housing 52 and is slidable therein. A stop ring 44 is secured within the auxiliary housing 42 by screws 45. This stop ring limitsmovement of the armature 26 away from the core member 22. A connecting rod 46 is threaded-into the end of the armature 25, as at El, and extends coaxially away from the armature through an opening 48 in the stop ring 44. The pole face end of the armature 26 is preferably slotted, as

at 5|, to provide a screw driver slot for holding the armature during the assembly and disassembly of the connecting rod iG. The'other end of the connecting rod ie is threaded into a tool carrier 49, as at 5B, the carrier beingjournaled for sliding movement in the extending end of the auxiliary housing d2. A compression spring 52 is disposed around the rod and between the stop ring 4-? and the tool carrier normally to bias the armature away from the stationary magnetic-member 22.

A tool or working instrumentality 53 is secured in the end of the carrier 49 beyond the connecting rod 15 as by threading at E4. The tool 53 may be made in any desired shape andof the proper material as may be required for specine uses such as etching metal, plastic orglass surfaces, cutting materials such as metal, glass An outer covering of insulating material 5l-fits over the outer-surfaceof theauxiliary housing member 32 and has an outer surface shaped to provide'a handle for the tool.

The mass of the moving parts including the armature 2%, connecting rod 46, tool carrier 4-9,

and the tool 53 is correlated with the strength of thespring 52 as well as to the alternating current frequency of the vpower source in such a way that moving parts vibrate or reciprocate at a-i'requency which is dependent upon the frequency of the power source. This cooperative relation is also preferably such that themagnetic force exerted upon the armature by the current flow through the windingtddurin a portion of the alternating currentcycle isabsorbed in the spring '52for release during aworking stroke at another portion of the cycle. The stationary core -member 22 is preferably adjusted to a position such that the armature closely approache the pole face thereof without actual engagement. Thus, the spring :52 absorbs .the full energy delivered by the magnet, and this energy is released during the .workingstroke-to project the tool against the work.

It will be observed that the cross sectionalarea of .the various portions of the housing andthe stationary core member 22 not only providesfiux paths of the desiredlowreluctance, but ispsufiicient to provide a massgreaterthan thatof the moving parts and thereby stabilize the tooland minimize vibration of the supporting structure. flhe novel construction ,of the magnetic. housing is simple and inexpensive, assembled readily, and enables the parts to be adjusted conveniently in service use. The magnet is utilized most efficiently in actuating the tool because all of the energy developed by the magnet during attraction of the armature is stored in the spring, and the full effect of this energy is applied to the tool to projectthe latter againstthe work.

=I. claim as my invention:

1. A magnetically operated tool having, in combination, a generally cylindrical coil having an axial .opening therethrough and adapted to be energized'by alternating current, a housing of :magnetic material enclosin said coil and having :axiallyalined flanges turned into opposite ends of said opening and supporting said coil, a core member projecting axially through one of said flanges beyond the inner end thereof and mounted for adjustment axially of its supporting flange, a tube rigid with and projecting from the other .end of said housing in alinement with said other flange, an armature slidable axially'of the latter flange and said tube for movement of its inner end toward and away from the end of said core member, a carrier slidably guided in theouter end of said tube, a'stop limiting the outward movement of-said armature, arod connecting said armature and said carrier, and a compression spring coiled about said rod and acting between said stop member and said car- ;rier to urge the latter outwardly and to be compressed-when said armatureis attracted to said core-member.

v2. A'magnetically operated tool'comprising, in combination, a housin including a pair of oppositely disposed cup-.like elements of magnetic material having axial bottom openings and inwardly extending flanges around the openings, a ,coil coaxial with the housing and surrounding said openings, said coil being wedged onto said flanges, ;a stationary core member of magnetic material adjustably secured in one of said cuplike housing elements and extending axially into the.coil,,an armature of magnetic material movably journaled in the opening in the other of said cup-like housing elements and extending into the coil toward the end-of the stationary core member, a connecting rod secured at one end to the armature and extending coaxially therewith awayfrom the coil, stop means limiting movement of the armature away from the stationary core membena tool carrier on the end of said rod, a compression spring encircling said .rod between said stop means and the tool carrier tip and normally biasing the armature away from the stationary core member and into contact with the stopmeans, and a tube enclosing saidspring and guiding said carrier.

3. In a magnetically operated tool, the combination comprising a housing of magnetic material having end walls and subsantially cylindrical side walls, said housing having an opening in one end thereof and inwardly extending projections having tapered outer Walls spaced from said side walls and converging axially :toward each other, said projections being .axially alined and spaced apart, ;a -,coil having opposite ends fittingsnugly over and wedged ontosaid tapered walls, an armature journaled for axial movement insaid openingzand extending into the coil-beyond the-end of one.ofsaid projections, the other projection constituting a core to .which said armatureis attracted when the coilisenergized, and resilient means biasing saidlarmature away fromsaid core. Y

4. In a magnetically operated tool, the combination of, a housing of magnetic material comprising cup-like halves disposed in opposed relation and having side and end walls, means securing the lips of said cups together in abutting relation, axial inwardly extending projections on said end walls and spaced from the side walls, said projections having tapered outer surfaces, and a solenoid type coil having tapered inner end surfaces fitting snugly over said projections.

5. In a magnetically operated tool, the combination of, a housing of magnetic material comprising cup-like halves disposed in opposed relation and having side and end walls, axial inwardly extending projections on the end walls and spaced from the side walls, said projections having tapered outer surfaces, and a solenoid type coil having tapered inner end surfaces fitting snugly over said projections, the side walls of said housing being alotted to limit eddy current losses and said flanges being axially slotted.

6. A magnetically operated tool having, in combination, two cups of magnetic material arranged with their lips overlapping and secured to each other, the bottoms of the cups having alined axial openings and flanges around the latter projecting into the cups, a coil within the cups encircling and supported on said flanges, a magnetic plug mounted in one of said flanges and projecting from the inner end thereof, a tube having one end projecting into the bottom opening of the other cup and secured rigidly to the latter, a magnetic cylinder slidable in said tube and the adjacent cup flange toward and from said plug, a stop within said tube limiting the outward movement of said cylinder, a rod within said tube 6 secured to said cylinder, and a spring coiled around the rod within said tube and urging said rod and cylinder outwardly.

7. A magnetically operated tool having, in combination, a generally cylindrical coil having an axial opening therethrough, a housing of magnetic material surrounding the coil and having axially alined flanges integral therewith and turned into opposite ends of the coil, said flanges projecting into opposite ends of said coil and wedged into the latter whereby to provide a firm support for the coil, a magnetic core member fitted in and projecting axially through one of said flanges and adapted for adjustment axially thereof, a tube having one end projecting into and rigidly secured to the other flange, an armature slidable in the latter flange and said tube, a tool carrier slidable in the opposite end of the tube, a rod connecting said armature and carrier, and a spring coiled around the rod and urging said carrier and armature in one direction.

ANDREW J. FRANCIS, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,490,276 Kenyon Apr. 15, 1924 1,678,278 Weyandt July 24, 1928 2,100,660 Greiner Nov. 30, 1937 2,225,967 Berman Dec. 24, 1940 2,268,687 Young Jan. 6, 1942 

